Such spray cans have been known for many years for different areas of application and for a variety of materials to be sprayed. They are sold by the millions, particularly in the household and do-it-yourself sector. Spray cans for paints and paint preparation materials are primarily used in the do-it-yourself sector. In the trades sector or in industrial production painting, coatings are usually applied by means of compressed-air, airless, air-supported airless or electrostatic atomization. Particularly in workshop or industrial auto repair painting, either low-pressure paint sprayers or high-pressure paint sprayers are used; the other methods mentioned above are used only to a lesser degree. High-pressure spraying is the most common painting method. However, even if the quality of the surface meets the requirements of production painting in the automotive industry or for repair painting, this painting method has the greatest "overspray" and achieves a degree of application effectiveness of only about 30% to 50%.
While compressed air atomization takes place at pressures of 1.5 to 5 bar in high-pressure spraying, atomization of the paint material in low-pressure spraying takes place at pressures in the range of 0.7 to 1.0 bar. This low-pressure spraying method requires high air volumes, which are produced with fans, among other things. Since the atomizer pressure must be limited to 0.7 bar in certain states of the United States, and, at the same time, a degree of application effectiveness of at least 65% is required, paint spraying devices marketed under the designation HVLP ("High Volume Low Pressure") have recently been developed. Compared with conventional compressed-air atomization at 3.5 to 4 bar, low-pressure spraying has the advantage that paint mist ("overspray") is avoided to a large extent, and therefore a high material yield as well as a significantly improved degree of application effectiveness is achieved.
Conventional spray cans are used only to a very slight extent by professional users such as auto repair shops or in industrial production painting because of their low paint output rate and their very uneven paint application; instead, they are used primarily in the do-it-yourself sector.